Paper-filler and process of making the same



T" E S 1 N F .i

WILL N. KOHJLINS, OF NEWARK, NEW JERSEY.

SAME.

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lto Drawing.

To all whom it may concern:

Be it known that 1, WILLIAM N. Konmms, a citizen of the United States, and a resident of Newark, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Paper- Fillers and Processes of Making the Same, of which the following is a description.

My invention relates to an improved pa-- per filler especially adapted for use in coating paper to produce the high glossy surfaces required on paper for books, catalogues, periodicals, etc, employed for wood cuts and photographic illustrations; and also to the process of making such filler.

Various fillers are at present employed in coating paper to provide the same with a glossy surface such as described, among them that known by the trade name of satin white. A. common form of satin white consists of a mixture of calcium sulfate, aluminum hydrate, calcium hydroxid and water, whichis disposedof to the trade in the form of a stid water paste.

The principal object of my invention is to produce a new and improved paper filler adapted for use in place of satin white and other paper fillers now employed by the trade, and by the use of which improved results are obtainable, There are certain drawbacks to the use of satin white as a paper filler. Tn applying fillers to the surface of paper, it is" customary to employ casein dissolved in an alkali. Satin white, however, tends to coagulate the casein, and accordingly it is necessary when applying this filler to use an excess of the alkali solvent for the casein in order to prevent coagulation of the latter and to obtain a coating on the paper which is at all satisfactory. Satin white is also crystalline and uneven in structure and on account of this the surface of paper coated therewith readily picks, especially in the operation of printing thereon. 4

T have found that by mixing a soluble magnesium salt with certain other material commonly used in making paper fillers ll obtain a product which will contain an insoluble magnesium compound and the use of which as a paper filler will be unaccompanied by the objectionable features described above. T preferably employ magnesium sulfate, as the soluble magnesium salt, and

Specification of Letters Patent. Patzgnfgqgffl Sept, 113 11921 Application filed February 2'7, 1919. Serial No. 279,645.

preferably mix the same with aluminum hydrate and an excess of calcium oxid and water. The solid matter or residue is then separated from the water and material in solution, and after a thorough washing is pressed to a stifi" pulp or paste. This product constltutes my improved paper filler and consists of a mixture of magnesium hydroxid (an insoluble magnesium compound), calcium sulfate, aluminum hydrate, and calcium hydroxid. The paper filler thus produced is amorphous and of a fine, uniform and smooth texture. It does not tend to coagulate casein and accordingly is easily and readily applicable to the surface of the paper. Moreover, it lies better on paper than satin white and other fillers now employed, produces a surface having a higher and better gloss, and because of its fine, compact and uniform texture the surface of paper coated therewith does not pick When being printed on. I believe these results are due entirely to the presence of the magnesium hydroxid which renders my pa per filler essentially difl erent from satin white, china clay, blancfixe and other fillers now commonly employed. While I prefer to employ aluminum hydrate as one of the ingradients of my paper filler, the same does not enter into the reactionwhich results in the production of the filler and may 'obvi ously be omitted.

While T have specifically described the preferred form of my paper filler and the process of making the same, it is to be understood that both the filler and the process are subject to various modifications without departure from the spirit of my invention and the scope of the appended claims.

Having now described my invention, what I claim as new and desire to protect by Letpers Patent of the United States is as folows:

1. A paper filler comprising a mixture containing magnesium hydroxid, calcium sulfate and calcium hydroxid.

2. A paper filler comprising a mixture containing magnesium hydroxid, calcium sulfate, aluminum hydrate and calcium hydroxid.

3. The process of making a paper filler, which comprises mixing magnesium sulfate with an excess of calcium 02nd and water.

4. The process. of making a paper filler,

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which comprises mixing magnesium sulfate with aluminum hydrate and an excess of calcium oxid.

5. The process of making a paper filler, which comprises mixing magnesium sulfate with aluminum hydrate and with an excess of calcium oxid and water.

6. The process of making a paper filler, which comprises mixing magnesium sulfate with aluminum hydrate and an excess of calcium oxid and water, and separating the solid matter in the mixture from the water and material in solution.

7. The process of making a paper filler,

which comprises mixing magnesium sulfate with aluminum hydrate and an excess of calcium oxid and water, separating the solid matter in the mixture from the water and material in solution, and then washing the solid matter so separated.

8. The process of makin a paper filler, which consists in mixing magnesium sulfate with aluminum hydrate and an excess of calcium oxid and water, separating the solid matter in the mixture from the water and material in solution, then washing the solid matter so separated, and then pressing such solid matter to a stifl paste.

9. The process of making a paper filler, which comprises mixing magnesium sulfate with an excess of calcium oxid and water,

' and separating the solid matter in the mixture from the water and material in solution.

10. The process of making a paper filler, which comprises mixing magnesium sulfate with an excess of calclum oxid and water, separating the solid matter in the mixture from the water and material in solution, and then washing the solid matter so separated.

11. The process of making a paper filler, which comprises mixing magnesium sulfate with an excess of calcium oxid and water, separating the solid matter in the mixture from the water and material in solution, then washing the solid matter so separated, and then pressing such solid matter to a stiff paste.

This specification signed this 19th day of 4 February 1919;

WILLIAM N. KOHLINS. 

